The effect of milk allowance on behavior and weight gains in dairy calves.

The objective of this study was to investigate how milk allowance affects body weight gains and behavior before, during, and after weaning in dairy calves. Fifty-six Holstein calves were randomly assigned at 1wk of age to 1 of 4 feeding treatments of whole pasteurized milk: 6, 8, 10, or 12 L/d. Milk allowance was reduced by 50% at d 42, and then reduced by 20% per day starting at d 50, so that calves were completely weaned at d 55. Calves were provided ad libitum access to calf starter and hay. Body weight was measured weekly from 2 to 10wk of age. Milk intake increased with milk allowance as intended, although actual intakes were lower than the treatment allowance (e.g., averaging 5.66±0.19 L on the 6-L treatment and 9.41±0.21 L on the 12-L treatment before weaning). Intake of calf starter was higher for calves that were fed less milk before weaning (averaging 0.25±0.03kg/d and 0.05±0.03kg/d on the 6-L and 12-L treatments, respectively) and also during the weaning period (averaging 1.15±0.13kg/d and 0.54±0.14kg/d on these same treatments), but we observed no effect after weaning. Time spent at the hay feeder did not differ with treatment. Average daily gain was higher for calves that were fed more milk, increasing from 0.77±0.04kg/d with the 6-L treatment to 0.90±0.03kg/d with the 12-L treatment. Before weaning, calves fed less milk engaged in more unrewarded visits to the milk feeder, averaging 11.1±0.73 visits/d with the 6-L treatment and 0.4±0.78 visits/d with the 12-L treatment. During weaning, calves fed less milk still had more unrewarded visits to the milk feeder than calves fed more milk (19.7±1.64 visits/d with the 6-L treatment versus 10.1±1.74 visits/d with the 12-L treatment), but treatments did not differ after weaning. We conclude that higher milk allowances result in weight gain advantages before weaning that can persist beyond weaning, and that the high number of unrewarded visits to the milk feeder by calves that were fed less milk are indicative of persistent hunger.